Formation of diether esters



- limited thereto.

Patented Dec. 19, 1950 UNITED STATES PATENT OFFICE Van Hook, lhilade'lphia, Pa, assignors to fBolnn & Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Application October 2 1948, Serial No. 52,603

5 C a ms- 1 This invention concerns the preparation of diether esters of the formula n'om lon coon wherein R" represents hydrogen or the -.-.-D.OOR group, R represents the residue of a neutral, non-tertiary, monohydric alcohol, ROI-I, and R. represents the residue of a neutral, non-tertiary,

monohydric alcohol, R'OI-I.

and the like. A small amount of such a coordinated complex of boron trifluoride or of boron trifiuoride is used in the reaction mixture, 0.01% to 1% thereof on the weight of the mixture being generally sufficient.

The alcohol R'OH is broadly any primary or secondary monohydric alcohol free of groups-reacting with an acid. It may be aliphatic, cycloaliphatic, arylaliphatic, or heterocyclic. It may be saturated or unsaturated, In the latter case, it may be mentioned if acyclic p -unsaturation is present, reaction temperatures should be held below 150 C. to avoid a rearrangement which occurs at 150 C. and higher in the case of this particular type of unsaturation.

Commonly R, the residue of the alcohol ROH, is a hydrocarbon group. It is most convenient to Work with such groups of not over twelve carbon atoms. Yet, this group is not It may contain inert substituents such as ether or thio-ether linkages. The following groups are illustrative of the types and sizes which may be used for R.Methyl, ethyl, isopropyl, propyl, butyl, isobutyl, sec..- butyl, amyl, hexyl, z-ethylbutyl, heptyl, isoheptyl, capryl, 2-ethylhexy1, octyl, isooctyl, nonyl. isononyl. decyl. dodecyl, .cetyl, stearyl. methallyl.

2 undecenyl, oleyl, cyclohexyl, methylcycloheggyl, tetrahy droben z yl, hexahydrobenzyl, ma nets, ylene hexahydrobenzyl, benzyl, methylbenzyl, b t l e y i m hsxv th li e h ethrl 1 ethyl, octoxyethyl, phenoxythyl, benzoxyethyl, ycl hexox et y rppoxvp opy e yp pyi. ethoxyethoxyethyl, butoxyethoxyethyl, dfiisobu tylphenogyethyl, diisobutylphenoxyethoxyethyl, ethy tb p buty h o hy h s m thus far recited may also occur as R in the ether esters.

I d t n e e a o e up m y eonam a l en or a n t e group, as in c l r' br me p l h e o iy h em t m m t 'lnitropropyl, nitrobutyl, and the like. The 1m, r ent n i ra for d te m inin h e e"? R is that it be unreactive to acids, since-the reaction of this invention utilizes catalysts which are strongly acidic.

When transetherification is involved, the alcoo BQH ul boi hi he an RQEI! 1 plete replacement of ROI-I by 12/03 is conveniently obtained. Otherwise, mixed ethers or a m ur of et rs m r u t Wh cw erthe ether esters used are unsaturated, n e a e of ne, e a whe l tma bo l h or lower than ROH it may even be the s ROIH- h fl-Biher r te e h r ma e. n ver d o a fi fi di th r m' sns e 9 19iether succinate, respectively.

Esters of the formula (B MGGHeQ R a a bl thr u h h cti n of ace ylene nd er f a enis a d. ill-OM0 i i e enc o a ydr us lk line catal stmple e det i s o thi Pr es ar i n an; plication Serial No. 52,607, filed (pctgilier 2 i 8,

y the process th e s i e th r ar sibte essi flifiis h ubsi tut p p o ate BQ 2QH H OQR and .fi.-,.ether.-substituted acrylates- These may be obtained in separate fractions. or mixtures thereof may be obtained. When the ether propionates are heated in the presence .of an alkaline or an acid catalyst and a mole of -alcg.- hol is separated per mole of propionate, the related ether acrylate results. This is a convene ient procedure when it is desirable to deal with less of the alcohol ROI-I in the process of invention. The details of the conversion of ether propionates to ether acrylates are relatediniap: plication serial No. 152,603, filed October 2, 9.518.

3 Along with the ether propionates and acrylates prepared by the reaction of acetylene on esters of carbonic acid, there are obtained ether succinates of the formula aoncooon and related maleates aocoooa CHCOOR The latter are derivable from the former by the procedure described above for converting diether propionates to ether acrylates.

In the reaction of acetylene and organic carbonates, the reaction is effected at C. to 110 C. in the presence of such strongly alkaline catalysts as alkali metal acetylides, alkali metal alcoholates, and quaternary ammonium alkoX- ides. Typical of these are lithium methoxide, sodium methoxide, sodium butoxide, sodium heptoxide, sodium dodecylate, potassium ethylate, potassium amylate, potassium octoxide, benzyl trimethyl ammonium methoxide, dibenzyl dimethyl ammonium ethoxide, tetramethyl ammonium methoxide, methylbenzyl trimethyl ammonium tert.-butoxide, and the like.

The organic carbonate, (RO)2CO, may contain as R any of the groups which have been shown above. It is preferable that R be a hydrocarbon group, particularly one of not over twelve carbon atoms, and that it be free from acyclic flrv-unsaturation, even though R, is not confined to hydrocarbons. It is especially convenient to have R an ethyl or methyl group, since the ethyl and methyl ether esters are particularly economical to make and to use.

Some typical ether esters which may be prepared by the method described above are methyl B-methoxyacrylate, methyl dB-dimethoxypropionate, dimethyl a,a-dimethoxysuccinate, dimethyl methoxymaleate, ethyl fi-ethoxyacrylate, ethyl ,8,fl-diethoxypropinate, diethyl a,ozdi8thOXysuccinate, diethyl ethoxymaleate, butyl B-butoxyacrylate, butyl Bfi-dibutoxypropionate, dlbllty1a,a. dibutoxysuccinate, dibutyl butoxymaleate, octyl dfi-dioctoxypropionate, cyclohexyl fifi-dicyclohexoxypropionate, benzyl 5,5 dibenzoxypropionate, ethoxyethyl 13,;8-diethoxyethylpropionate, ethylthioethyl p-ethylthioethoxyacrylate, methallyl p,p-methalloxypropionate, etc.

To illustrate the preparation of B e-diether propionates and diether succinates, there is given the following example of the preparation of these ether esters. The apparatus used for reaction of acetylene and organic carbonate comprised a five-liter flask equipped with a gas-tight stainless steel stirrer, the blades of which scraped the bottom of the flask. For the preparation of the catalyst, 225 grams of anhydrous ethyl alcohol was placed in the flask and thereto was gradually added sodium in small cubes until thirty grams of this metal had been used. The sodium was dissolved; the excess alcohol was then evaporated under reduced pressure. The sodium ethylate remained as a dry powder. There was added to the flask at this point 2200 grams of anhydrous diethyl carbonate.

The flask was then equipped with gas inlet and outlet tubes, a manometer, and thermometer. The flask was flushed with nitrogen and heated to about 80 C. Acetylene was passed into the system. This gas was taken from a commercial cylinder but was scrubbed with water and sul- Iuric acid and was then passed over soda-lime.

When the rate of absorption of acetylene became very slow, the flask was cooled and the flow of acetylene was discontinued. Dilute acetic acid was added to the system to destroy the alkaline catalyst. Two layers formed in the flask. The upper, oily layer was separated and fractionally distilled.

A forerun was obtained at normal pressure. It consisted of ethyl alcohol and ethyl carbonate. Distillation was continued under reduced pressure. A fraction was taken off at 65 to 75 C./2 to 4 mm. This was found to consist of about 10% of ethyl fl-ethoxyacrylate and 90% of ethyl [3,B-diethoxypropionate. There was then obtained at 75 C./4 mm. a fraction of pure ethyl ;9,/3diethoxypropionate. There was then taken oil? a fraction between 75 C./& mm. and 114 C./3 mm. which was a mixture of ethyl 13,,6- diethoxypropionate and diethyl a,a-diethoxysuccinate. At l14-115 C./3-4 mm., there was then obtained a fraction consisting of diethyl a,u-diethoxysuccinate. On further distillation, a fraction containing this succinate with some diethyl a-ethoxymaleate was obtained.

The alcohol ROH may be used in stoichiometric excess of the ether esters and serve as a solvent. There may also be used an inert organic solvent, such as a naphtha, or an aromatic hydrocarbon such as benzene, toluene, or xylene, or a chlorinated hydrocarbon.

The reaction between the alcohol ROH and ester (RO)nC(R")Cl-I11COOR is efiected in the presence of a boron trifluoride catalyst between about 20 C. and 200 0., preferably 100 C. to 145 C. The reaction may be effected under normal, increased, or reduced pressure. When the reaction has been carried on, the catalyst is destroyed, as by washing with water or neutralizing with an alkaline agent, such as sodium carbonate, potassium carbonate, sodium hydroxide, or the like. The reaction product may then be obtained. Unreacted alcohol or solvent may be stripped off. The reaction product,

is then isolated, usually by distillation at low pressure.

When the starting material is one of the unsaaturated ether esters, a mole of alcohol adds thereto to give ouroomooon If the reaction temperature is raised, particularly if the alcohol ROH is taken off by distillation, the RO- group is displaced. There is then obtained the compound,

(R'O) 2C(R") CHZCOOR Similarly, when the starting compound (R0) 20 (R' CH2COOR is heated with two moles of ROH, there results (R'O) 2C(R) CHzCOOR A mixture of seventy-two grams (0.5 mole) of ethyl B-ethoxyacrylate, twenty-three grams (0.5 mole) of anhydrous ethanol, and five milliliters of a boron trifiuoride-ethyl ether complex formed from an equal volume of each in a stoppered flask was allowed to stand at C. for sixty hours. It was then washed with water until the water layer was neutral. The organic layer was then dried over anhydrous magnesium Sulfate and distilled. There were obtained 10.5 grams of a mixture composed of ethyl fiethoxyacrylate and 65% ethyl d/i diethoxypropionate (as estimated from refractive index), Which distilled at 4752 C./0.3 mm. and had a refractive index, 11 of 1.4240, and 57.5 grams of ethyl flfi-diethoxyprcpionate, which distilled at 52-54 C./0.3 mm, had a refractive index, n of 1.4120, and gave upon analysis a saponification equivalent of 106. Ethyl 5,,8-diethoxypropionate (Col-11304) has a refractive index, 71 of 1.4122 and a theoretical saponification equivalent of 190. The total yield of this product was 72%.

Example 2 A mixture of seventy-two grams (0.5 mole) of ethyl ,B-ethoxyacrylate, thirty-seven grams (0.5 mole) of n-butanol, and five milliliters of the boron trifluoride-ethyl ether complex was allowed to stand in a stoppered flask for fifteen hours. After this time, it was washed with water until the Water layer became neutral. The organic layer was then dried over anhydrous magnesium sulfate and distilled. There were obtained ten grams of a mixture of ethyl [i-ethoxyacrylate and ethyl fl-ethoxy-B-n-loutoxypropionate, which distilled at --65 C./0.4 mm. and had a refractive index, 11. of 1.4312, and eighty-six grams ofethyl ,0-ethoxy-,8-n-butoxypropionate, which distilled at -102 C./0.4 mm. and had a refractive index, 12, of 1.4220. The eighty-six grams of this product represents a yield of 79%. Upon redistillation, the product boiled at C./ 0.45 mm., had a refractive index, 72 of 1.4200,, a density.

of 0.9556, and gave upon analysis a saponification equivalent of 216 and a molecular refraction, MRD, of 57.73. Ethyl B-ethoxy-B-n-butoxypropionate K111112204) has a theoretical saponifica tion equivalent of 218. and a molecular refraction, MRD, of 57.94.

Example 3 A mixture of seventy-two grains (0.5 mole) of ethyl B-ethoxyacrylate, 148 grams (2.0 moles) of n-butanol, and three milliliters of the boron trifluoride-ethyl ether complex was heated under grams of unreacted butanol, which distilled at 33-59 C,./50 mm. The residue was cooled and diluted with ether, washed with water until the water layer became neutral, and the organic layer dried over anhydrous calcium sulfate and distilled. There were obtained 8.5 grams of unreacted ethyl B-ethoxyacrylate, which distilled at 52 -82 C. 0.2 mm. and had a refractive index,

n of 1.4459, and seventeen grams of a mixture of ethyl fl-ethoxyacrylate and ethyl ltd-di-(nbutoxymropionate, which distilled at 82 C./0.2 mm. and had a refractive index, c of 1.4327. There was then obtained seventy-five grams of ethyl Bfi-di-(n-butoxy)propionate, which distilled at 95-107 C./0.2 mm., had a refractive index, n of 1.4265, and gave upon analysis a saponification equivalent of 244. Ethyl lw-di-(nbutoxy)propionate (Cal-12604) has a theoretical saponification equivalent of 246.

Example 4 A mixture of 190 grams (1.0 mole) of ethyl 5,5- diethoxypropionate, 352 grams (4.0 moles) of namyl alcohol, and four milliliters of the boron trifluoride-ethyl ether complex was heated under a two-foot packed column. There was obtained on distillation ninety five grams of ethanol, which boiled at 78 C., while the pot temperature rose from 119 to C. The column was removed and 134 grams of excess ar'nyl alcohol separated therefrom at 138-148 C. while the pot temperature rose from 160 to 215' C. The residue was cooled, diluted with ether, and washed with water until the Water layer became neutral, The organic layer was then dried over anyhdrous calcium sulfate and distilled from a Claisen flask. After removal of ether, there were obtained eighteen grams of unreacted n-amyl alcohol, which distilled at 29-8 C./1 mm.. twelve grams of a mixture of n amyl alcohol, ethyl fi-ethoxyacrylate, and ethyl B,,6-di-(namyloxy)propionate, which distilled at 38-10'2 C./0.75 mm. and had a refractive index. 11. of 1.4422, and 187 grams of ethyl [rc-di-(n-amyloxy)propionate, which distilled at 102-143 C./0.8 mm. and had a refractive index, 11 of 1.4366. The 187 grams of product represents a yield of 58%. The product, upon redistillation. boiled at 107-109 C./0.2 mm., had a refractive index, 12, of 1.4337; a density,

of 0.9322; and gave upon analysis a saponification equivalent of 266, a molecular refraction, MED, of 76.49, a carbon content of 66.01 and a hydrogen content of 11.18%. Corresponding values for ethyl B,[ -di-(n-amyloxy)propionate (0151553004) are: Molecular refraction, MR1), 76.41; saponification equivalent, 274; carbon content, 65.69%, and hydrogen content, 10.95%.

Example 5 A mixture of 190 grams (1.0 mole) of ethyl p 9 di'ethoxypropionate, 296 grams (4,0 moles) of nbutanol, and two milliliters of the boron trifluoride-ethyl ether complex was heated in a flask under a two-foot packed column. There were obtained on distillation ninety-one grains of ethanol. which distilled at 78-83 C. and had a refractive index, 11 of 1.3620, and seventy-two grams of excess n-butanol, which distilled at 1l2-117 C. and had a refractive'index, n of 1.3960, while the pot temperature rose from 107 C. to 140 C. The residue was cooled and washed with water until the water layer became neutral. The organic layer was dried over anhydrous magnesium sulfate and distilled. There were 0t tained an additional nine grams of n-butan'o'l, which distilled at 24-62 C./1 mm. and had a refractive index, 11 of 1.4090, twenty-six grams of a mixture of ethyl B-ethoxyacrylate and ethyl ,dfi-di-(n butoxy)propionate, which distilled at 62-9-5 C./0.3 mm. and had a refractive index. u of 1.4371, and grams of ethyl B,p-'-di-(nbutoxynaropionate, which distilled at 78f-87" C./0.1 mm. and had a refractive index. n of 1.4240. The 180 grams represents a yield of 73%. Upon redistillation, the product boiled at 92-94 C./0.3 mm.; had a refractive index, 11 of 1.4230; a density,

of 0.9257, and gave the following analytical values: Molecular refraction, MRD, 67.67; saponification equivalent, 245; carbon content, 63.27%, and hydrogen content, 10.53%. Corresponding values for ethyl efi-di-(n-butoxy) ropionate (ClIiHZGO) are: Molecular refraction, MR1), 67.17; saponification equivalent, 246; car bon content, 63.41%, and hydrogen content, 10.57%.

Example6 A mixture of 131 grams (0.5 mole) of diethyl a,a-diethoxysuccinate, 111 grams (1.5 moles) of n-butanol, and fifteen milliliters of the boron trifiuoride-ethyl ether complex was heated in a flask under a two-foot column. There were obtained on distillation 43.5 grams of ethanol, which distilled at 78 to 85 C. and has a refractive index, n of 1.3619, while the pot temperature rose to 145 C., and thirty-nine grams of unreacted n-butanol, which distilled at 64-67 C./80 mm. and had a refractive index, 11 of 1.3965. An attempt to continue the distillation at this point in a high vacuum led to decomposition. The residue was cooled and washed with water until the water layer became neutral. The organic layer was dried over anhydrous calcium sulfate and distilled from a Claisen flask. There were obtained sixteen grams of diethyl nbutoxymaleate, C./0.25 min. and had a refractive index, 11,3, of 1.4491, seventy-one grams of a mixture of 74% diethyl n-butoxymaleate and 26% diethyl 04,11- di-(n-butoxy)succinate (as estimated from saponification numbers), which distilled at 118- 121 C./0.25 mm. and had a refractive index n of 1.4479, and twenty-eight grams of a mixture of 50% maleate and 50% succinate. The yield of combined succinate and maleate was 81%.

Example 7 A mixture of 131 grams (0.5 mole) of diethyl m,a-diethoxysuccinate, 102 grams (1.0 mole) of 2-ethylbutanol, and one milliliter of the boron trifiuoride-ethyl ether complex was heated in a Claisen flask. There was obtained on distillation forty grams of ethanol, which distilled at 84-l01 C. with superheating and had a refractive index, n of 1.3719. The distillation was continued in vacuo. There were obtained twenty-two grams of unreacted 2-ethylbutanol, which distilled at 38-95 C./.03 mm. had a refractive index, 11 of 1.4220, thirteen grams of a mixture of 40% diethyl 2-ethylbutoxymaleate and 60% diethyl a,a-di(2-ethylbutoxy)- succinate (as estimated from refractive index), which distilled at 95-122 C./0.25 mm. and had a refractive index, n of 1.4470, seventy-four grams of a mixture of 35% maleate and 65% succinate, which distilled at 122-132 C./0.2- mm. and had a refractive index, n of 1.4460, and sixty-eight grams of a mixture of maleate and 85% succinate, which distilled at 119132 C./0.1 mm. and had a refractive index, 12,3 of 1.4435. Redistillation of the last fraction yielded a sample of pure diethyl u,a-di(2-ethylbutoxy)- succinate, which distilled at 125-128 C./0.1 mm., had a refractive index, 11, of 1.4410, and gave the following analytical values: Saponiwhich distilled at 109-118' fication equivalent, 182; carbon content, 64.20%, and hydrogen content, 10.31%. Corresponding values for ethyl a,a-di-(2-ethylbutoxy)succinate (C2OI'I3806) are: Saponification equivalent, 187; carbon content, 64.17%, and hydrogen content, 10.22%.

The methods shown above may also be applied to the interaction of the same ether esters and mercaptans. The alcohol ROI-l is displaced and the mercapto group, RS-, is introduced. Thus, ethyl dp-diethoxypropionate yields ethyl 8,;8-dibutylthiopropionate when heated with butyl mercaptan in the presence of a boron trifiuoride atalyst. Similarly, diethyl diethoxysuccinate yields diethyl a,a-diethylthiosuccinate.

The reaction here disclosed is one of considerable utility. It provides a method of obtaining ether esters with a great variety of ether groups. These are useful as softeners, plasticizers, solvents, and chemical intermediates.

We claim:

1. A process which comprises reacting together between 20 C. and 200 C. in the presence of a boron trifiuoride catalyst an formula ROH and an ether ester of the formula nonoofifloooa and separating from the reaction mixture the compound,

avonccmcoor.

in the above formulas n representing an integer from one to two, inclusive, R" representing a member of the class consisting of hydrogen and the COOR group, R representing the residue of a neutral, non-tertiary, monohydric alcohol, ROH, which residue does not react with an alkali and which contains not over twelve carbon atoms. and R representing the residue of a neutral, non-tertiary, monohydric alcohol which does not react with acids which boils higher than the alcohol ROI-l, and which contains not over eighteen carbon atoms.

2. A process which comprises reacting together between 20 C. and 200 C. in the presence of a boron trifiuoride catalyst an alcohol of the formula ROI-I and an ether ester of the formula (RO),.CCHnCOOR removing about n moles of the alcohol ROH from the reaction mixture per mole of said ether ester. and separating the compound,

in the above formulas n representing an integer from one to two, inclusive, R" representing a member of the class consisting of hydrogen and the -COOR group, R representing the saturated hydrocarbon residue of not over two carbon atoms of a non-tertiary, monohydric aliphatic alcohol, ROI-I, and R representing the hydrocarbon residue of a non-tetiary, monohydric alcohol which is free of acyclic [3,7-11I1S2Ll1llldtl01l which boils higher than ethyl alcohol, and which contains not over eighteen carbon atoms.

3. A process which comprises reacting together between 20 C. and 200 C. in the presence of a boron trifiuoride catalyst an alcohol of the formula R'OH and an ether ester of the formula (R0) zCHCHzCOOR removing about two moles of the alcohol ROH alcohol of the 2,535,011 9 10 from the reaction mixture, and separating the removing n moles of ethyl alcohol, and separatcompound, ing the compound (R'O) ZCHCHZCOOR (RO) 2CHCH2COOC2H5 in the above formulas R representing an alkyl n bein .v H 5 g an integer from one to two and B being group of not over two carbon atoms and R rep- 5 an alkyl v group whlch is larger than the ethyl resentmg an alkyl group larger than R and of group and contains not over twelve carbon atoms.

not over twelve carbon atoms. 7

4. Aprocess which comprises reacting together i' fi g P9 of 01mm 4 m Whmh 18 e between 20 C. and 200 C. in the presence of a boron trifiuoride catalyst an alcohol of the formula R'OH and the compound WILLARD J. CROXALL.

No references cited. 

1. A PROCESS WHICH COMPRISES REACTING TOGETHER BETWEEN 20* C. AND 200*C. IN THE PRESENCE OF A BORON TRIFLUORIDE CATALYST AN ALCOHOL OF THE FORMULA R''OH AND AN ETHER ESTER OF THE FORMULA 